Recording tape cassettes commonly have in one edgewall an opening which is blocked by a tab cored out from either the cover or the base of the cassette. After a recording has been made, accidental erasure is prevented by manually breaking off the tab. This allows a feeler on the cassette deck to enter the opening, and such movement of the feeler disables the erase and record functions. If one later wishes to make a new recording, one covers the record-lockout opening with a piece of the tape and then removes the tape to protect the new recording. U.S. Pat. No. 4,352,473 (Satoh et al.) shows a typical record-lockout tab at the left-hand corner of FIG. 1. An elaborate record-lockout mechanism is disclosed and claimed in U.S. Pat. No. 3,826,489 (Watkins, Jr.), but it also must be manipulated manually. If one were forget to actuate the record-lockout mechanism, the recording might later be accidentally erased.